From patchwork Thu Jan 30 20:04:40 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Arvind Sankar X-Patchwork-Id: 206606 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-9.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH, MAILING_LIST_MULTI, SIGNED_OFF_BY, SPF_HELO_NONE, SPF_PASS, USER_AGENT_GIT autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 9F7CBC35246 for ; Thu, 30 Jan 2020 20:04:51 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 78422214AF for ; Thu, 30 Jan 2020 20:04:51 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727161AbgA3UEu (ORCPT ); Thu, 30 Jan 2020 15:04:50 -0500 Received: from mail-qk1-f193.google.com ([209.85.222.193]:45052 "EHLO mail-qk1-f193.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727614AbgA3UEu (ORCPT ); Thu, 30 Jan 2020 15:04:50 -0500 Received: by mail-qk1-f193.google.com with SMTP id v195so4177880qkb.11; Thu, 30 Jan 2020 12:04:49 -0800 (PST) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:from:to:cc:subject:date:message-id:in-reply-to :references:mime-version:content-transfer-encoding; bh=YnfSmd5BvkLFsh0nPNy/3uEL0TluYTwz+zLsYY8/uCw=; b=pwrfNcIe49di8w/alX63HlrtfvV1GzAa6nmYt1rx8vT6A6F0r+2DzIg93+27CmMbwu 2Dg92EYNKXO+X5qJrpRtQm0Sg8pU04axDfOl9t9nIIWUDg+MKXiAOO7qaBxK9uMOCcnc PmcKUlbN5hbpf5HSYnvYakMJESKckVoU+o4PWCByKpM2rFI+Y173gzytkF2daYo7JSmY aSe6jgkezBTU40TvpYIPOTVk7j8n10E04HIp96fklEyZtfEhODCMKEg2ailoOf6+8Wy/ LIjmcI0/rv85Kim07kqrxFcvay9RRpeSAZuX6yW4FDJ00zlUorEH2rOiBd5LIYDfMZ5j +OCg== X-Gm-Message-State: APjAAAVAepp2g92efaAvmoRwkUEVVLV4i2bvtIXBCtqJyxeBI/FSMEoc xtSCOQzPvU9YlrV7tbSFP8w= X-Google-Smtp-Source: APXvYqxZv8KxrwfLJ4RsleKR7BkXYUmiK80t5OGV/op/UYcaY1r/kLf5QnLszxdj9dCnT6tj2MTAXQ== X-Received: by 2002:a05:620a:1663:: with SMTP id d3mr7240564qko.204.1580414689272; Thu, 30 Jan 2020 12:04:49 -0800 (PST) Received: from rani.riverdale.lan ([2001:470:1f07:5f3::b55f]) by smtp.gmail.com with ESMTPSA id k15sm3262865qkk.103.2020.01.30.12.04.48 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 30 Jan 2020 12:04:48 -0800 (PST) From: Arvind Sankar To: Thomas Gleixner , Ingo Molnar , Borislav Petkov , "H. Peter Anvin" , Jonathan Corbet , Ard Biesheuvel Cc: linux-efi@vger.kernel.org, x86@kernel.org, linux-doc@vger.kernel.org Subject: [PATCH 8/8] Documentation/x86/boot: Correct segment requirements for 64-bit boot Date: Thu, 30 Jan 2020 15:04:40 -0500 Message-Id: <20200130200440.1796058-9-nivedita@alum.mit.edu> X-Mailer: git-send-email 2.24.1 In-Reply-To: <20200130200440.1796058-1-nivedita@alum.mit.edu> References: <20200130200440.1796058-1-nivedita@alum.mit.edu> MIME-Version: 1.0 Sender: linux-efi-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-efi@vger.kernel.org 64-bit mode has no segment/GDT requirements as it does not really use segment registers. The entry code loads null descriptors into the data and stack segment registers. Signed-off-by: Arvind Sankar --- Documentation/x86/boot.rst | 9 +++------ 1 file changed, 3 insertions(+), 6 deletions(-) diff --git a/Documentation/x86/boot.rst b/Documentation/x86/boot.rst index 3e13b7d57271..df2bf8abbbc1 100644 --- a/Documentation/x86/boot.rst +++ b/Documentation/x86/boot.rst @@ -1396,12 +1396,9 @@ In 64-bit boot protocol, the kernel is started by jumping to the At entry, the CPU must be in 64-bit mode with paging enabled. The range with setup_header.init_size from start address of loaded kernel and zero page and command line buffer get ident mapping; -a GDT must be loaded with the descriptors for selectors -__BOOT_CS(0x10) and __BOOT_DS(0x18); both descriptors must be 4G flat -segment; __BOOT_CS must have execute/read permission, and __BOOT_DS -must have read/write permission; CS must be __BOOT_CS and DS, ES, SS -must be __BOOT_DS; interrupt must be disabled; %rsi must hold the base -address of the struct boot_params. +interrupt must be disabled; %rsi must hold the base address of the +struct boot_params. As 64-bit mode does not really use segments, there +are no special requirements on the segment registers or descriptors. EFI Handover Protocol =====================